我国南方地区、北方地区和西北地区都有种植的经济作物是[ ]
A.棉花
B.花生
C.水稻
D.小麦
答案:A
With such a lot of work on hand, he ____ to the cinema last night. [ ]
A. oughtn't to go
B. shouldn't have gone
C. mustn't go
D. wouldn't go
产生IL-2的细胞是()。
A.巨噬细胞
B.肥大细胞
C..T淋巴细胞
D.B细胞
E.嗜酸性粒细胞